PRAGUE, July 31 - Czech ex-president Vaclav Havel and Nobel Peace Prize winner Desmond Tutu called on Olympic athletes on Thursday to speak up on human rights in China during the Beijing Olympics next month.

Havel, a human rights campaigner jailed by Communist rulers before their government fell in 1989, and the South African Archbishop Tutu said in an open letter the International Olympic Committee (IOC) should let athletes know about the suppression of liberties in China.

"It is necessary for all Olympians to be able to learn about the real situation in China and to point out human rights violations freely whenever and wherever, in line with their conscience," the letter said.

"We call on the International Olympic Committee to make that possible."

Beijing has drawn criticism from international rights groups for acts such as the arrest of a prominent dissident and the censorship of some websites, and scrutiny of its foreign policy and rights records is mounting ahead of the August 8-24 Games.

The IOC has worked hard to keep Games-linked events and ceremonies as politics-free as possible.

But athletes should speak out and the IOC should allow them to, said the letter, also signed by Chinese dissident Wei Jingsheng and European Parliament Vice-President Edward McMillan-Scott.

"To speak of the conditions of human rights ... cannot be in violation of the Olympic Charter," the letter said.

"To speak of human rights is not politics; only authoritarian and totalitarian regimes try to make it so. To speak of human rights is a duty."

Havel irked the Chinese government on several occasions during his 1989-2003 tenure as president, mainly through his personal friendship with the exiled Tibetan leader, the Dalai Lama.